REYKJAVÍK, Iceland — For 360 days a year, Iceland is home to just 290,000 people, three massive glaciers and legions of Björk fans, but for five days each year, the capital city opens its indie-rock heart for the über-hip Iceland Airwaves music festival.

For its seventh-annual incarnation, which ended Sunday, Iceland Airwaves heated up the chilly city with a sultry new theme: the pursuit of sexiness. Most of the more than 140 bands that played this year — including Juliette and the Licks, Fiery Furnaces, Junior Senior, the (International) Noise Conspiracy and the Zutons — eagerly embraced that theme with electric live shows that packed around 4,000 people into six main venues and a series of smaller clubs.

For five days, bands mingled with fans and the press while watching underground acts, enjoying a drink and grabbing the late-night Icelandic "delicacy," pylsurs (a.k.a. hot dogs). Airwaves is beloved for its late-night shows (some bands don't take the stage until 2:30 a.m.) and an intimate atmosphere that allows fans to race past Björk on their way into a club, or chat up Juliette Lewis at the Saturday afternoon "hangover party."

Denmark's Junior Senior were fixtures at the festival, showing up at different venues every night. During their own set, the pair got the packed room moving with songs like their 2003 hit, "Move Your Feet." The previous evening, platinum-tressed Norwegian dance-club sensation Annie, known for her sugary hit "Chewing Gum," donned an '80s-inspired off-the-shoulder top and stretch pants to perform tracks off her 2004 debut, Anniemal.

Juliette and the Licks headlined on Friday evening, with Lewis — clad in a skin-tight white shirt and equally clingy white pants — piquing the crowd's excitement with her thrashing, Iggy Pop-inspired movements and crowd-surfing stints. The Zutons' diminutive saxophonist, Abi Harding, gave Lewis some stiff competition in the category of favorite female musician, though, captivating the audience at the Reykjavík Art Museum (formerly a prison).

Icelandic acts like the keyboard-happy Apparat Organ Quartet, rockers Singapore Sling, and Gus Gus (who played the very first Airwaves festival), shone. Brooklyn's underground success story Clap Your Hands Say Yeah drew one of the festival's biggest crowds with lines wrapping around the city's central square, while fellow Brooklynites New Radio, who've yet to appear on the radar Stateside, made a roomful of new fans with their alternately sweet and rocking cello-driven sound and singer Atarah Valentine's androgynous cabaret-inspired style.

An opportunity for Iceland to make its mark on the musical map, the Airwaves festival kicked off in 1999 at an airplane hangar, with acid jazz/ dance-music group Thievery Corporation as one of the featured performers. In its early years, the festival functioned as more of an industry showcase but has since become a way to introduce Icelandic bands to the world, and international bands to Icelanders.

The festival has drawn acts like the Bravery, the Hives, the Flaming Lips, Keane, the Shins, Sahara Hotnights, TV on the Radio, Fatboy Slim and Citizen Cope to the country's most densely populated city (about 170,000 people live there).

The main event that sets Iceland Airwaves apart from all other underground music festivals is its annual hangover party, which finds fans and artists leaving the confines of the city to lounge in the country's famous Blue Lagoon — a warm, milky-blue geothermal pool — and listen to a set by Icelandic DJ Hermigervill. Try finding that at New York's CMJ Music Marathon.